1. Field of the Invention
The invention relates to an apparatus for handling sleeves on press cylinders having a slit annular inherently stiff holding element which is matched to the outer shape of the sleeve and clamps around the sleeve on its circumferential surface with a clamping force so that the sleeve can be held with a form fit.
2. Description of the Related Art
U.S. Pat. No. 5,802,975 discloses a device for handling sleeves on cylinders, which displaces printing-forme sleeves or rubber coated sleeves over the free end of cantilever-mounted printing unit cylinders. For this purpose, a sleeve gripping system is provided on the corresponding printing unit cylinders, which grips the surface of the sleeve with a guide element with a force fit at a predeterminable axial position and displaces the sleeve in the axial direction on the printing unit cylinder using a pneumatic cylinder.
U.S. Pat. No. 4,549,923 discloses dismantling pieces which enclose a sleeve in a ring shape and may be clamped around the sleeve by clamping means. One of the dismantling pieces is designed in the form of an open ring, which is provided at its opposite ends with lugs which may be pulled together by a screw in such a way that the annular part is clamped around the sleeve. Another design shows an annular dismantling piece which is divided into two separate halves, between which the sleeve is clamped. Provided on both halves in each case are grip pieces, on which springs or pneumatic cylinders act in order to clamp the sleeve.
U.S. Pat. No. 6,250,223 likewise relates to an apparatus for removing a printing sleeve from a cantilever-mounted cylinder. As already disclosed by U.S. Pat. No. 5,802,975, contact elements that can be positioned axially on the circumference of the printing sleeve are provided and are set against the printing sleeve in order to produce a frictional force. For this purpose, in one exemplary embodiment from U.S. Pat. No. 6,250,223, a band of inherently rigid material is provided, which is matched to the external shape of the printing sleeve. Using a clamping device, this band may be clamped around the printing sleeve, analogous to the dismantling piece from U.S. Pat. No. 4,549,923.
In all off these prior art apparatuses, there is the risk of damaging the printing sleeve.
It is an object of the present invention to provide an apparatus for handling sleeves on press cylinders which ensures that a printing sleeve is picked up and held stably and which rules out damage.
According to the invention, the holding element has mutually facing ends defining a slit having a width. At least one clamp urges the ends toward each other so that the clamping force is limited by the width of the slit. A device for expanding the holding element is provided, so that the clamping force on the sleeve can be released. The apparatus according to the present invention makes it possible, in an advantageously simple way, to push sleeves (printing-plate sleeves with or without seam or rubber blanket sleeves) onto press cylinders and to pull them off.
Using the apparatus according to the present invention, sleeves can be picked up carefully and at the same time stably and without damage, such as indentations or bends, can advantageously be avoided.
In particular the shape of sleeves of large diameter can be stabilized in an excellent manner by the apparatus according to the present invention, which means that pushing such sleeves on and pulling them off is significantly simplified.
Using a slit holding element, the apparatus can advantageously be adapted to the differences in diameter when the sleeve is widened in order to push it on or pull it off the cylinder. At the same time, this measure makes it simple to pick the sleeve up in the apparatus.
In an apparatus designed in accordance with the present invention, an unstable sleeve becomes a relatively stiff, easily handled tube.
The apparatus makes it possible to bring the printing sleeves into a predefined position in relation to their circumferential and their axial position, that is to say they can be fitted to a press cylinder with an accurate fit and in register.
Using a mounting aid, the fitting of a sleeve to a press cylinder can be simplified still further, since the said aid permits the sleeve to be pushed on without canting.
As a result of the provision of damping elements on the apparatus according to the present invention, vibrations of the sleeves can be damped, which means that an advantageous reduction in the noise nuisance is achieved.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.